Is there any benefit to putting 2 doors in 1 doorframe?

If you open a placed door, you can place another door in the opening as long as it’s a different tier or type. The open door will close and overlay the one you closed…

Will they both take the same damage from one explosive or will one shield the other to a degree, and will one of them despawn on server restart? (Stay tuned for the last one.)

The doors are still layered on top of each other after a server restart.